Solid state interface devices, such as touch pads and touch screens, are popular and in use on a wide variety consumer electronic products and motor vehicle systems. However, these solid state interface devices typically fail to provide a user with any form of tactile feedback as a result of their solid state nature. The human user of the interface device therefore is not able to experience haptic sensations that assist and inform the user during interaction with the interface device.
There is a need for human interface devices for electronic devices used in motor vehicles, computers, music players, telephones and myriad other electronic devices. For example, modern motor vehicles, especially automobiles but also aircraft, trains and watercraft, contain very complex interfaces.
Drivers/pilots need to manage vast amounts of data: vehicle status (e.g., speed, engine speed, cruise control status), climate control, entertainment, communications, navigation, etc. This has the dual effects of leading to very complex instrument panels and requiring significant visual attention, which should be focused on the road or path ahead.
One approach to mitigating these dual effects is the use of haptic feedback. For instance, the iDrive used in some BMW motor vehicles comprises a single knob that controls up to 700 vehicle functions. The haptic feel and behavior of the knob are under computer control and are programmed to be context sensitive.
For instance, the knob can be made to feel and act like a tuning controller for a radio station or like a temperature adjust for a climate control system. The iDrive has numerous drawbacks as well. For instance, it uses a menu system that can be difficult to learn as well as distracting to use, and it offers only one haptic degree of freedom (turning of the knob) such that it fails to exploit the human ability to move in higher dimensional spaces.
T. Watanabe and S. Fukui in “A method for controlling tactile sensation of surface roughness using ultrasonic vibration”, in Proc. IEEE International Conference on Robotics and Automation, Nagoya, Japan (1995) describe a device based on variable friction generated by bulky ultrasonic Langevin-type vibrators wherein the user's finger moves in one dimension along the display surface with no finger position or other feedback.
Nara et al. in “Surface acoustic wave tactile display”, Computer Graphics and Applications, IEEE, (2001), pp. 53-56, describe a device based on variable friction with one-dimension finger feedback, but the device requires the user's finger to interact with a steel ball slider on the display in a manner that filters the haptic effect.
U.S. Pat. No. 7,148,875 discloses a haptic feedback device for touchpads and other touch controls wherein haptic feedback is provided by direct application of a force or motion to a touch surface in a manner that the user's finger can feel the force or motion. To this end, one or more actuators are coupled to the touchpad to apply a force directly to its surface. In one embodiment, the actuator can comprise a piezoelectric actuator, a voice coil, a pager motor, or a solenoid coupled to the touchpad.
Copending application U.S. Ser. No. 11/726,391 filed Mar. 21, 2007, of common assignee discloses haptic devices that can provide indirect haptic feedback and virtual texture sensations to a user by modulation of friction of a touch surface of the device in response to one or more sensed parameters and/or in response to time (i.e. independent of finger position). The sensed parameters can include, but are not limited to, sensed position of the user's finger, derivatives of sensed finger position such as velocity and/or acceleration, direction of motion of the finger relative to the surface, and/or sensed finger force or pressure on the surface. The touch surface is adapted to be touched by a user's bare finger, thumb or other appendage and/or by an instrument such as a stylus held by the user.